xref: /openbmc/linux/include/linux/mux/driver.h (revision 17b5b576)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * mux/driver.h - definitions for the multiplexer driver interface
4  *
5  * Copyright (C) 2017 Axentia Technologies AB
6  *
7  * Author: Peter Rosin <peda@axentia.se>
8  */
9 
10 #ifndef _LINUX_MUX_DRIVER_H
11 #define _LINUX_MUX_DRIVER_H
12 
13 #include <dt-bindings/mux/mux.h>
14 #include <linux/device.h>
15 #include <linux/ktime.h>
16 #include <linux/semaphore.h>
17 
18 struct mux_chip;
19 struct mux_control;
20 
21 /**
22  * struct mux_control_ops -	Mux controller operations for a mux chip.
23  * @set:			Set the state of the given mux controller.
24  */
25 struct mux_control_ops {
26 	int (*set)(struct mux_control *mux, int state);
27 };
28 
29 /**
30  * struct mux_control -	Represents a mux controller.
31  * @lock:		Protects the mux controller state.
32  * @chip:		The mux chip that is handling this mux controller.
33  * @cached_state:	The current mux controller state, or -1 if none.
34  * @states:		The number of mux controller states.
35  * @idle_state:		The mux controller state to use when inactive, or one
36  *			of MUX_IDLE_AS_IS and MUX_IDLE_DISCONNECT.
37  * @last_change:	Timestamp of last change
38  *
39  * Mux drivers may only change @states and @idle_state, and may only do so
40  * between allocation and registration of the mux controller. Specifically,
41  * @cached_state is internal to the mux core and should never be written by
42  * mux drivers.
43  */
44 struct mux_control {
45 	struct semaphore lock; /* protects the state of the mux */
46 
47 	struct mux_chip *chip;
48 	int cached_state;
49 
50 	unsigned int states;
51 	int idle_state;
52 
53 	ktime_t last_change;
54 };
55 
56 /**
57  * struct mux_chip -	Represents a chip holding mux controllers.
58  * @controllers:	Number of mux controllers handled by the chip.
59  * @mux:		Array of mux controllers that are handled.
60  * @dev:		Device structure.
61  * @id:			Used to identify the device internally.
62  * @ops:		Mux controller operations.
63  */
64 struct mux_chip {
65 	unsigned int controllers;
66 	struct mux_control *mux;
67 	struct device dev;
68 	int id;
69 
70 	const struct mux_control_ops *ops;
71 };
72 
73 #define to_mux_chip(x) container_of((x), struct mux_chip, dev)
74 
75 /**
76  * mux_chip_priv() - Get the extra memory reserved by mux_chip_alloc().
77  * @mux_chip: The mux-chip to get the private memory from.
78  *
79  * Return: Pointer to the private memory reserved by the allocator.
80  */
mux_chip_priv(struct mux_chip * mux_chip)81 static inline void *mux_chip_priv(struct mux_chip *mux_chip)
82 {
83 	return &mux_chip->mux[mux_chip->controllers];
84 }
85 
86 struct mux_chip *mux_chip_alloc(struct device *dev,
87 				unsigned int controllers, size_t sizeof_priv);
88 int mux_chip_register(struct mux_chip *mux_chip);
89 void mux_chip_unregister(struct mux_chip *mux_chip);
90 void mux_chip_free(struct mux_chip *mux_chip);
91 
92 struct mux_chip *devm_mux_chip_alloc(struct device *dev,
93 				     unsigned int controllers,
94 				     size_t sizeof_priv);
95 int devm_mux_chip_register(struct device *dev, struct mux_chip *mux_chip);
96 
97 /**
98  * mux_control_get_index() - Get the index of the given mux controller
99  * @mux: The mux-control to get the index for.
100  *
101  * Return: The index of the mux controller within the mux chip the mux
102  * controller is a part of.
103  */
mux_control_get_index(struct mux_control * mux)104 static inline unsigned int mux_control_get_index(struct mux_control *mux)
105 {
106 	return mux - mux->chip->mux;
107 }
108 
109 #endif /* _LINUX_MUX_DRIVER_H */
110